1 //===- BasicValueFactory.cpp - Basic values for Path Sens analysis --------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 //  This file defines BasicValueFactory, a class that manages the lifetime
11 //  of APSInt objects and symbolic constraints used by ExprEngine
12 //  and related classes.
13 //
14 //===----------------------------------------------------------------------===//
15 
16 #include "clang/StaticAnalyzer/Core/PathSensitive/BasicValueFactory.h"
17 #include "clang/StaticAnalyzer/Core/PathSensitive/APSIntType.h"
18 #include "clang/StaticAnalyzer/Core/PathSensitive/SVals.h"
19 #include "clang/StaticAnalyzer/Core/PathSensitive/Store.h"
20 #include "clang/StaticAnalyzer/Core/PathSensitive/StoreRef.h"
21 #include "llvm/ADT/APSInt.h"
22 #include "llvm/ADT/FoldingSet.h"
23 #include "llvm/ADT/ImmutableList.h"
24 #include "llvm/ADT/STLExtras.h"
25 #include <cassert>
26 #include <cstdint>
27 #include <utility>
28 
29 using namespace clang;
30 using namespace ento;
31 
32 void CompoundValData::Profile(llvm::FoldingSetNodeID& ID, QualType T,
33                               llvm::ImmutableList<SVal> L) {
34   T.Profile(ID);
35   ID.AddPointer(L.getInternalPointer());
36 }
37 
38 void LazyCompoundValData::Profile(llvm::FoldingSetNodeID& ID,
39                                   const StoreRef &store,
40                                   const TypedValueRegion *region) {
41   ID.AddPointer(store.getStore());
42   ID.AddPointer(region);
43 }
44 
45 void PointerToMemberData::Profile(
46     llvm::FoldingSetNodeID& ID, const DeclaratorDecl *D,
47     llvm::ImmutableList<const CXXBaseSpecifier *> L) {
48   ID.AddPointer(D);
49   ID.AddPointer(L.getInternalPointer());
50 }
51 
52 using SValData = std::pair<SVal, uintptr_t>;
53 using SValPair = std::pair<SVal, SVal>;
54 
55 namespace llvm {
56 
57 template<> struct FoldingSetTrait<SValData> {
58   static inline void Profile(const SValData& X, llvm::FoldingSetNodeID& ID) {
59     X.first.Profile(ID);
60     ID.AddPointer( (void*) X.second);
61   }
62 };
63 
64 template<> struct FoldingSetTrait<SValPair> {
65   static inline void Profile(const SValPair& X, llvm::FoldingSetNodeID& ID) {
66     X.first.Profile(ID);
67     X.second.Profile(ID);
68   }
69 };
70 
71 } // namespace llvm
72 
73 using PersistentSValsTy =
74     llvm::FoldingSet<llvm::FoldingSetNodeWrapper<SValData>>;
75 
76 using PersistentSValPairsTy =
77     llvm::FoldingSet<llvm::FoldingSetNodeWrapper<SValPair>>;
78 
79 BasicValueFactory::~BasicValueFactory() {
80   // Note that the dstor for the contents of APSIntSet will never be called,
81   // so we iterate over the set and invoke the dstor for each APSInt.  This
82   // frees an aux. memory allocated to represent very large constants.
83   for (const auto &I : APSIntSet)
84     I.getValue().~APSInt();
85 
86   delete (PersistentSValsTy*) PersistentSVals;
87   delete (PersistentSValPairsTy*) PersistentSValPairs;
88 }
89 
90 const llvm::APSInt& BasicValueFactory::getValue(const llvm::APSInt& X) {
91   llvm::FoldingSetNodeID ID;
92   void *InsertPos;
93 
94   using FoldNodeTy = llvm::FoldingSetNodeWrapper<llvm::APSInt>;
95 
96   X.Profile(ID);
97   FoldNodeTy* P = APSIntSet.FindNodeOrInsertPos(ID, InsertPos);
98 
99   if (!P) {
100     P = (FoldNodeTy*) BPAlloc.Allocate<FoldNodeTy>();
101     new (P) FoldNodeTy(X);
102     APSIntSet.InsertNode(P, InsertPos);
103   }
104 
105   return *P;
106 }
107 
108 const llvm::APSInt& BasicValueFactory::getValue(const llvm::APInt& X,
109                                                 bool isUnsigned) {
110   llvm::APSInt V(X, isUnsigned);
111   return getValue(V);
112 }
113 
114 const llvm::APSInt& BasicValueFactory::getValue(uint64_t X, unsigned BitWidth,
115                                            bool isUnsigned) {
116   llvm::APSInt V(BitWidth, isUnsigned);
117   V = X;
118   return getValue(V);
119 }
120 
121 const llvm::APSInt& BasicValueFactory::getValue(uint64_t X, QualType T) {
122   return getValue(getAPSIntType(T).getValue(X));
123 }
124 
125 const CompoundValData*
126 BasicValueFactory::getCompoundValData(QualType T,
127                                       llvm::ImmutableList<SVal> Vals) {
128   llvm::FoldingSetNodeID ID;
129   CompoundValData::Profile(ID, T, Vals);
130   void *InsertPos;
131 
132   CompoundValData* D = CompoundValDataSet.FindNodeOrInsertPos(ID, InsertPos);
133 
134   if (!D) {
135     D = (CompoundValData*) BPAlloc.Allocate<CompoundValData>();
136     new (D) CompoundValData(T, Vals);
137     CompoundValDataSet.InsertNode(D, InsertPos);
138   }
139 
140   return D;
141 }
142 
143 const LazyCompoundValData*
144 BasicValueFactory::getLazyCompoundValData(const StoreRef &store,
145                                           const TypedValueRegion *region) {
146   llvm::FoldingSetNodeID ID;
147   LazyCompoundValData::Profile(ID, store, region);
148   void *InsertPos;
149 
150   LazyCompoundValData *D =
151     LazyCompoundValDataSet.FindNodeOrInsertPos(ID, InsertPos);
152 
153   if (!D) {
154     D = (LazyCompoundValData*) BPAlloc.Allocate<LazyCompoundValData>();
155     new (D) LazyCompoundValData(store, region);
156     LazyCompoundValDataSet.InsertNode(D, InsertPos);
157   }
158 
159   return D;
160 }
161 
162 const PointerToMemberData *BasicValueFactory::getPointerToMemberData(
163     const DeclaratorDecl *DD, llvm::ImmutableList<const CXXBaseSpecifier *> L) {
164   llvm::FoldingSetNodeID ID;
165   PointerToMemberData::Profile(ID, DD, L);
166   void *InsertPos;
167 
168   PointerToMemberData *D =
169       PointerToMemberDataSet.FindNodeOrInsertPos(ID, InsertPos);
170 
171   if (!D) {
172     D = (PointerToMemberData*) BPAlloc.Allocate<PointerToMemberData>();
173     new (D) PointerToMemberData(DD, L);
174     PointerToMemberDataSet.InsertNode(D, InsertPos);
175   }
176 
177   return D;
178 }
179 
180 const PointerToMemberData *BasicValueFactory::accumCXXBase(
181     llvm::iterator_range<CastExpr::path_const_iterator> PathRange,
182     const nonloc::PointerToMember &PTM) {
183   nonloc::PointerToMember::PTMDataType PTMDT = PTM.getPTMData();
184   const DeclaratorDecl *DD = nullptr;
185   llvm::ImmutableList<const CXXBaseSpecifier *> PathList;
186 
187   if (PTMDT.isNull() || PTMDT.is<const DeclaratorDecl *>()) {
188     if (PTMDT.is<const DeclaratorDecl *>())
189       DD = PTMDT.get<const DeclaratorDecl *>();
190 
191     PathList = CXXBaseListFactory.getEmptyList();
192   } else { // const PointerToMemberData *
193     const PointerToMemberData *PTMD =
194         PTMDT.get<const PointerToMemberData *>();
195     DD = PTMD->getDeclaratorDecl();
196 
197     PathList = PTMD->getCXXBaseList();
198   }
199 
200   for (const auto &I : llvm::reverse(PathRange))
201     PathList = prependCXXBase(I, PathList);
202   return getPointerToMemberData(DD, PathList);
203 }
204 
205 const llvm::APSInt*
206 BasicValueFactory::evalAPSInt(BinaryOperator::Opcode Op,
207                              const llvm::APSInt& V1, const llvm::APSInt& V2) {
208   switch (Op) {
209     default:
210       assert(false && "Invalid Opcode.");
211 
212     case BO_Mul:
213       return &getValue( V1 * V2 );
214 
215     case BO_Div:
216       if (V2 == 0) // Avoid division by zero
217         return nullptr;
218       return &getValue( V1 / V2 );
219 
220     case BO_Rem:
221       if (V2 == 0) // Avoid division by zero
222         return nullptr;
223       return &getValue( V1 % V2 );
224 
225     case BO_Add:
226       return &getValue( V1 + V2 );
227 
228     case BO_Sub:
229       return &getValue( V1 - V2 );
230 
231     case BO_Shl: {
232       // FIXME: This logic should probably go higher up, where we can
233       // test these conditions symbolically.
234 
235       if (V1.isSigned() && V1.isNegative())
236         return nullptr;
237 
238       if (V2.isSigned() && V2.isNegative())
239         return nullptr;
240 
241       uint64_t Amt = V2.getZExtValue();
242 
243       if (Amt >= V1.getBitWidth())
244         return nullptr;
245 
246       if (V1.isSigned() && Amt > V1.countLeadingZeros())
247           return nullptr;
248 
249       return &getValue( V1.operator<<( (unsigned) Amt ));
250     }
251 
252     case BO_Shr: {
253       // FIXME: This logic should probably go higher up, where we can
254       // test these conditions symbolically.
255 
256       if (V2.isSigned() && V2.isNegative())
257         return nullptr;
258 
259       uint64_t Amt = V2.getZExtValue();
260 
261       if (Amt >= V1.getBitWidth())
262         return nullptr;
263 
264       return &getValue( V1.operator>>( (unsigned) Amt ));
265     }
266 
267     case BO_LT:
268       return &getTruthValue( V1 < V2 );
269 
270     case BO_GT:
271       return &getTruthValue( V1 > V2 );
272 
273     case BO_LE:
274       return &getTruthValue( V1 <= V2 );
275 
276     case BO_GE:
277       return &getTruthValue( V1 >= V2 );
278 
279     case BO_EQ:
280       return &getTruthValue( V1 == V2 );
281 
282     case BO_NE:
283       return &getTruthValue( V1 != V2 );
284 
285       // Note: LAnd, LOr, Comma are handled specially by higher-level logic.
286 
287     case BO_And:
288       return &getValue( V1 & V2 );
289 
290     case BO_Or:
291       return &getValue( V1 | V2 );
292 
293     case BO_Xor:
294       return &getValue( V1 ^ V2 );
295   }
296 }
297 
298 const std::pair<SVal, uintptr_t>&
299 BasicValueFactory::getPersistentSValWithData(const SVal& V, uintptr_t Data) {
300   // Lazily create the folding set.
301   if (!PersistentSVals) PersistentSVals = new PersistentSValsTy();
302 
303   llvm::FoldingSetNodeID ID;
304   void *InsertPos;
305   V.Profile(ID);
306   ID.AddPointer((void*) Data);
307 
308   PersistentSValsTy& Map = *((PersistentSValsTy*) PersistentSVals);
309 
310   using FoldNodeTy = llvm::FoldingSetNodeWrapper<SValData>;
311 
312   FoldNodeTy* P = Map.FindNodeOrInsertPos(ID, InsertPos);
313 
314   if (!P) {
315     P = (FoldNodeTy*) BPAlloc.Allocate<FoldNodeTy>();
316     new (P) FoldNodeTy(std::make_pair(V, Data));
317     Map.InsertNode(P, InsertPos);
318   }
319 
320   return P->getValue();
321 }
322 
323 const std::pair<SVal, SVal>&
324 BasicValueFactory::getPersistentSValPair(const SVal& V1, const SVal& V2) {
325   // Lazily create the folding set.
326   if (!PersistentSValPairs) PersistentSValPairs = new PersistentSValPairsTy();
327 
328   llvm::FoldingSetNodeID ID;
329   void *InsertPos;
330   V1.Profile(ID);
331   V2.Profile(ID);
332 
333   PersistentSValPairsTy& Map = *((PersistentSValPairsTy*) PersistentSValPairs);
334 
335   using FoldNodeTy = llvm::FoldingSetNodeWrapper<SValPair>;
336 
337   FoldNodeTy* P = Map.FindNodeOrInsertPos(ID, InsertPos);
338 
339   if (!P) {
340     P = (FoldNodeTy*) BPAlloc.Allocate<FoldNodeTy>();
341     new (P) FoldNodeTy(std::make_pair(V1, V2));
342     Map.InsertNode(P, InsertPos);
343   }
344 
345   return P->getValue();
346 }
347 
348 const SVal* BasicValueFactory::getPersistentSVal(SVal X) {
349   return &getPersistentSValWithData(X, 0).first;
350 }
351